Abstract : Several helmets were tested to determine the optimum shell t ickness and type of suspension for maximum protection during high-energy collisions. Comfort during normal use was also evaluated. The velocity of the helmet at impact was measured with an electronic counter having an accuracy within one count. Data are given on the optimum thickness for epoxy resin shells and the most satisfactory suspension. A test procedure is described for determining the ba ic crash helmet configuration which then can be modified for specific application.